The nature of bacteria acquired in the health care setting differs significantly from bacteria found in a community setting, primarily in their resistance to antibiotic therapy. Abundant evidence exists, however, that the hospital environment itself contributes to the problem by harboring virulent strains of bacteria, fungi, and viruses, and that many disinfection methods commonly used are ineffective and may actually spread contaminants. These contaminants are present on objects, and in particular, instruments, such as endoscopes. These instruments must be decontaminated between uses.
Multiple needs exist to provide disinfection or decontamination of objects that are not suitable for treatment by an autoclave or similar methods. These include, but are not limited to, the exterior of mail, fruits and certain other food items, medical instruments, food handling devices, and other objects that are contaminated with biological hazards.
Examples of such objects are flexible and rigid endoscopes. Endoscopy is a common procedure in modern medical practices. Endoscopes are used to examine and surgically manipulate the sinus cavities, upper and lower gastrointestinal tracts, lung fields, larynx, and intra-abdominal spaces. These endoscopes may have interior channels or conduits that are difficult to reach and disinfect. Relatively straightforward methods exist to disinfect endoscopes that have simple architecture, such as those that do not have interior channels, although the working life of the endoscopes is lessened by chemical degeneration of the seals. An ongoing problem has been the reliable disinfection of endoscopes that have interior channels. These channels are used to inject liquid irrigants, suction, and to pass flexible instruments such as biopsy forceps. These types of interior chambers have represented a challenge to infection control efforts.
Ultraviolet irradiation, particularly in the C bandwidth (2537 Angstroms), when given in adequate doses is lethal to all known pathogens. Ultraviolet irradiation in the C bandwidth (UV-C) is being used to disinfect water supplies, air duct systems, and recently entire patient care areas. The use of UV-C to disinfect endoscopes has not been accomplished to date primarily because of the unavailability of methods of delivering UV-C radiation to interior channels, the unavailability of methods of measuring cumulative dosing that assure adequate decontamination, and the unavailability of methods of measuring UV-C levels that are delivered to the object to be decontaminated.
Microbes are uniquely vulnerable to the effects of light at wavelengths at or near 2537 Angstroms, due to the resonance of this wavelength with molecular structures. For the purposes of this document, the term UV-C is used for a wavelength of light being utilized for its germicidal properties, this wavelength being in the region of 2537 Angstroms.
Recent advances in light emitting diodes (LEDs) have provided the ability to generate UV-C within endoscope channels with sufficient intensity to decontaminate and/or sterilize such channels. Also, the method of measuring an accumulating total energy delivered has recently been developed relative to area disinfecting methods, and effective dose ranges have been established.
The United States Food and Drug Administration and the United States Center For Disease Control and Prevention define disinfection as the use of a chemical procedure that eliminates virtually all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial endospores) on inanimate objects. There are three levels of disinfection: high, intermediate, and low. High-level disinfection kills all organisms, except high levels of bacterial spores, and is effected with a chemical germicide cleared for marketing as a sterilant by the Food and Drug Administration. Intermediate-level disinfection kills mycobacteria, most viruses, and bacteria with a chemical germicide registered as a “tuberculocide” by the Environmental Protection Agency (EPA). Low-level disinfection kills some viruses and bacteria with a chemical germicide registered as a hospital disinfectant by the EPA. For the purposes of this document, “disinfection” includes all three of these levels, although disinfection is not achieved solely by chemical means by the process described herein.